reboot is done

src/shell/exec.c

@@ -85,7 +85,8 @@ void shell_init(void)
 			           "poweroff, echo, color, merdella\n");
 			break;
 		case REBOOT:
-			kprintf(0, "rebooting\n");
+			kprintf(0, "rebooting...\n");
+			reboot();
 			break;
 		case POWEROFF:
 			kprintf(0, "powering off\n");

src/shell/reboot.c

@@ -0,0 +1,32 @@
+#include "sys/io.h"
+#include <stdint.h>
+
+#define KBD_INTERFACE 0x64
+
+/* keyboard interface bits */
+#define KBD_BIT_KDATA 0 /* keyboard data */
+#define KBD_BIT_UDATA 1 /* user data */
+
+#define KBD_IO    0x60 /* keyboard IO port */
+#define KBD_RESET 0xFE /* reset CPU command */
+
+#define bit(n) (1 << (n)) /* Set bit n to 1 */
+
+/* Check if bit n in flags is set */
+#define check_flag(flags, n) ((flags) & bit(n))
+
+void reboot(void)
+{
+	uint8_t tmp;
+
+	asm volatile("cli"); /* disable all interrupts */
+	do {
+		tmp = inb(KBD_INTERFACE); /* empty user data */
+		if (check_flag(tmp, KBD_BIT_KDATA))
+			inb(KBD_IO); /* empty keyboard data */
+	} while (check_flag(tmp, KBD_BIT_UDATA));
+	outb(KBD_INTERFACE, KBD_RESET); /* pulse CPU reset line */
+loop:
+	asm volatile("hlt"); /* if that didn't work, halt the CPU */
+	goto loop;           /* if a NMI is received, halt again */
+}